Published in Report No. CP/SEAM-2002/06: Structural Engineering and Applied Mechanics, December 20, 2002, pages 1-19. Department of Civil & Environmental Engineering, California Polytechnic State University, San Luis Obispo.
This investigation is concerned with application of nonlinear fluid viscous dampers for asymmetric-plan systems. For this purpose, the behavior of nonlinear fluid viscous dampers is summarized first followed by the effects of damper nonlinearity on seismic response of asymmetric systems. It is shown that the peak force in nonlinear damper tends to be smaller compared to linear damper. However, this is true only for values of V / ůo less that a certain threshold value; for larger values of V / ůo, the force in nonlinear damper may become larger· than that in the linear damper. While the damper nonlinearity tends to limit the damper force, it leads to smaller equivalent damping at velocities larger than the design velocity. The investigation on the seismic response of one-story, one-way asymmetric linear and nonlinear systems with linear and nonlinear fluid viscous dampers shows that the damper nonlinearity leads to only minor (less than 10%) reduction in edge deformations, base shear, and base torque except for linear systems and for nonlinear systems with long periods (Ty > 0.5 sec). For short-period (Ty < 0.5 sec) linear and nonlinear systems, damper nonlinearity may be used to achieve significant reduction (of the order to 30%) in flexible-edge deformations. Furthermore, the effects of plan-asymmetry on the flexible-edge are significantly reduced, especially for short period systems. The effects on stiff-edge deformation, base shear, and total damping force are modified very little by the damper nonlinearity. The modification for the base torque and total damping torque is slightly larger.
Civil and Environmental Engineering